A friend and I have been doing research on a recipe and he encountered a statement to the effect that the result should be around "6% acidity." I am not familiar with what this would mean in the context of food, and need help parsing what this phrase means and how to tell when a resource is using the taste sensation, as opposed to the pH, sense of the word.

To my understanding, acidity in coffee (as an example) is not actual acidity; "acidity" refers to [the] flavor note, not to the actual acid content; coffee is relatively low in acid. Its pH averages around 5.0 - 5.1(src).

If a cooking resource refers to a percent of acidity, is this a measure somehow related to the pH of the food? Or is it possible the resource is making the same "flavor note" comparison (i.e. where coffee turns between having a bright tongue, or not)

Either way, how would I go about trying to prepare some solution that would replicate the taste/sensation of "6% acidity"?

I am roughly imagining some quantity x of [consumable acid, e.g. vinegar] and y of water; would that approximate the taste/sensation?

I am pretty sure we'll need to know what the recipe was for in order to get some answerable context, although I agree that is unusual phrasing.
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Katey HWSep 7 '11 at 14:06

@Katey Will do, it wasn't in a recipe though, it was in some kind of discussion of typical recipes and benchmarks in them.
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mfgSep 7 '11 at 14:07

I think acids in food are general weak acids, so if that percentage is a percent by mass (or pre-mixing volume or anything else) it still won't have a clean relationship to pH.
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Jefromi♦Sep 7 '11 at 14:17

In brewing, fruit flavorings are ranked by acidity, with citric acid in lime or lemon contributing the most at 5-7%. So the reference could be interpreted to mean about as tart as a lemon.
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Erik OlsonSep 7 '11 at 18:30

2 Answers
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In wine-making, at least, acidity is a function of three different types of acid. Because those types of acid matter to the final product, wine making supply stores and websites provide several inexpensive ways of determining acidity. Two described here are an acid titration kit and a pH meter. When making wine last year I used an acid titration kit and it couldn't have been simpler. You take a sample of your liquid, the indicator solution, and a reactor solution. Based on how much of the reactor you have to add to change the color of the original sample you can get your acidity in a percent.

In my experience with the wine we noticed the acidity in our grape juice (that was on its way to becoming wine) more by the burning sensation on our hands where we touched the grapes as we crushed them or in our mouths when we drank - our solution started out seriously acidic. It was hard to taste a difference between too acidic and just right.

If you have a liquid recipe and want to get the acidity exactly right, consider using acid titration.

Am sure that the type of acid used would be the determining factor though.

It seems that the acid percentage is the molar weights of the acid and the dilutant, say 6 grams of pure acid to 100 grams of water; 6/100 = 6%. Am not a chemist but seem to remember that the same proportions of dilutant to acid results in varying Ph, depending on the type of acid.

The apple cider vinegar I use as a baste on my smoked joints of pork is shown on the label as being 5% acid - it's actually quite pleasant & makes tasty dressings and slaw.

Can't imagine what recipe is being looked at, have made saurbrauten which, in the recipe I used, called for quite a lot of vinegar; am sure though that the final acidity was substantially less than 6%.

An easy way to find out would be to prepare the recipe and taste it, you can buy Ph indication strips easily enough, which should give you (with a bit of calculation) an idea as to whether or not you are in the 6% acid range.